1. Field of the Invention
The present invention relates to a shift device with a synchronizer for a transmission in which pressing force applied to a shift sleeve can be amplified into larger pressing force acting on a synchronizer ring while gears of the transmission are shifted, thereby reducing operating force necessary for a driver or an actuator.
2. Description of the Related Art
A shift device with a synchronizer for a transmission of this kind is disclosed in Japanese unexamined patent application publication No. 09-89002. This conventional shift device is used to shift gears between fifth-speed and reverse speed. It has a hub, a shift sleeve, a synchronizer ring capable of being pressed toward a fifth-speed gear, and a plurality of lever members provided between the synchronizer ring and the hub. The lever members change an axial pressing force from the shift sleeve toward the fifth-speed into an amplified axial pressing force that acts on the synchronizer ring when the sleeve is being moved toward the fifth-speed gear, and they transmit the axial pressing force from the sleeve toward the reverse gear (in an opposite direction to the fifth-speed gear) to the fifth-speed gear so that the synchronizer ring and the fifth-speed gear are synchronized. This enables the sleeve rotating due to inertia of a clutch disc to stop the rotation thereof, and then the sleeve is smoothly engaged with the reverse gear. Thus the shift device can be a simple device using the lever members at lower manufacturing costs to decrease gear engagement noise in an operation to shift to the reverse-speed position.
In the operation to shift to the reverse-speed position, the friction torque of the synchronizer ring presses the lever members to extend them outwardly in the radial direction to prevent the sleeve from further advancing before the synchronization between the fifth-speed gear and the sleeve is ended. When the synchronization is ended, the blocking force of the synchronizer ring due to the friction torque vanishes. Accordingly, the slanted surfaces formed on the inner surface of the sleeve press the lever members inwardly in the radial direction, so that the sleeve moves toward and engages with the reverse gear.
The conventional shift device with the synchronizer, however, encounters the following problems.
In the conventional shift device, the lever members are formed like a semicircular shape when they are seen from their front sides, because they are inserted in the hollows formed on the hub. In this case, when the hollows of the hub are small in their radial lengths, the radial lengths of arm portions of the lever members inevitably become shorter in a state where end portions of the arm portions can contact with projections of the ring. As a result, the axial thicknesses of the lever members are needed to be larger in order to ensure the stiffness thereof. The lever members with larger thickness are difficult to be punched out in a press process.
It is, therefore, an object of the present invention to provide a shift device with a synchronizer for a transmission which overcomes the foregoing drawbacks and in which necessary stiffness of lever members can be ensured and the lever members can be easily formed in a press process.